Considering the applications we produce today (small, targeted, "micro" applications), I value integration tests way more than unit tests (along with acceptance tests). They provide much more realistic testing on your application with the only downside of being hard to pinpoint which part of your code is the problem when you have failures. I have been writing integration tests for the .NET based HTTP applications which use MongoDB as the data storage system on same parts and I pulled out a helper into library which makes it easy to stand up a MongoDB server, create a random database and clean up the resources afterwards. The library is called MongoDB.Testing and it’s on NuGet, GitHub. Usage is also pretty simple and there is also a a few samples I have put together.